An PCI 32765 increase in islands and lateral sand bars in the reach is also shown in Fig. 5C. Analysis indicates that the reach gained 23,600 m2 of island area in 40 km of reach (the length of the reach is limited by the extent of the aerial photos). The areal extent of island area in 1999 was 150% greater

in 1950. Additionally, the island morphology has shifted from in-channel islands (indicative of the pre-dam river) to large islands attached to the outside of meander bends with distinctive distributary channels running through them. These are essentially former islands that have become attached to the banks as a result of excess sediment cutting off side channels. The Reservoir-Dominated selleck screening library Interaction reach is located 140–190 km downstream from the Garrison Dam. Reservoir effects vary both annually and seasonally due

to changing reservoir levels creating a recognizable deltaic morphology. The Reservoir-Dominated Interaction reach is characterized by aggrading islands, sand bars, and the flooded meander bends (former meanders that have been flooded by the reservoir). 9 of 11 sites indicate deposition greater than the natural variability (269 m2). Fig. 4A is typical of cross sections in this area and shows al decrease in cross-sectional area of 411 m2. No suitable historic aerial imagery was available for this section of the river but current conditions indicate higher levels of low elevation sand bars than other sections of the river. The active extent of this reach can migrate drastically

from year to year depending on the reservoir level (as much as 160 km longitudinally, Fig. 6). Although the 50 km reach encompasses most of the delta in a typical discharge year, changes in releases from either dam can substantially change the active extent of the reach. Consequently, the depositional morphology and ultimately the Reservoir-Dominated Interaction reach can have a broader spatial distribution (Fig. 6A and B) than can be accounted for by a single year (insets A1 and A2, B1 and Cyclooxygenase (COX) B2). Although the lake level and backwater effects are highly spatially and temporally variable, the most recent set of aerial photos indicate the area of maximum deposition encompasses only this 50 km section of river. The morphology of this reach changes with varying lake levels. Islands, flooded meander scrolls, and deltaic splays are alternatively exposed and flooded. A large numbers of dead trees from flooding and those washed downstream litter the landscape and are present in channel. The Reservoir reach (Lake Oahe) is remarkably stable. This reach extends from approximately 190 km to just upstream of the Oahe Dam; 512 km downstream from Garrison Dam. Cross-sections in this section extend into the first 100 km into this reach. All 12 cross sections in the Oahe reach shows deposition greater than natural variability from 1963 to 1989 (269 m2).